Classification of Spinal Cord Injuries

Topic Overview

Spinal cord injuries (SCIs) can be
classified based on function (how much feeling and movement you have) or on
where the damage occurred. When a nerve in the spinal cord is injured, the
nerve location and number are often used to describe how much damage there is.
For example, a C7 injury is associated with the seventh cervical nerve of the
neck and its effect on feeling and movement. Saying you are a C7 communicates
that you can feed yourself and partially dress yourself but may need help
bathing, and so on. C7 is known as the functional level of injury. These
classifications are often used by people who have SCIs to describe
themselves.

The
spinal cord is surrounded by protective rings of bone called
vertebrae. The vertebrae and spinal nerves are
organized into
segments, starting at the top of the spinal cord. Within each segment, the vertebrae and nerves are numbered. The segments are as follows:

Cervical. The neck area contains 7 cervical vertebrae (C1 through
C7) and 8 cervical nerves (C1 through C8). Cervical SCIs usually cause loss of
function in the chest, arms, and legs. Cervical injuries can also affect
breathing and bowel and bladder control.

Thoracic. The chest area
contains 12 thoracic vertebrae (T1 through T12) and 12 thoracic nerves (T1
through T12). The first thoracic vertebra, T1, is the vertebra where the top
rib attaches to the spine. Thoracic SCIs usually affect the chest and the legs.
Injuries to the upper thoracic area can affect breathing. Thoracic injuries can
also affect bowel and bladder control.

Lumbar. The lumbar area
(between the chest area and the pelvis) contains 5 lumbar vertebrae (L1 through
L5) and 5 lumbar nerves (L1 through L5). Lumbar SCIs usually affect the hips
and legs. Lumbar injuries can also affect bowel and bladder
control.

Sacral. The sacral area (from the pelvis to the end of the
spine) contains 5 sacral vertebrae (S1 through S5) and 5 sacral nerves (S1
through S5). Sacral SCIs also usually affect the hips and legs. Injuries to the
upper sacral area can also affect bowel and bladder control.

The higher the damage occurs on the spinal
cord, the more of the body is affected. This is because the nerves in the area
of a vertebra
control body parts in that area. When the spinal cord is damaged, messages
cannot "jump over" the damaged area. This means that messages sent from the brain
cannot make it to body parts below the damaged area, and vice versa. Thus, the
body at and below the level of injury is affected.

For example, in
an injury to the spinal nerves in the neck area (C1 through C8), messages are
stopped in the neck area. This usually results in at least some
paralysis of the chest, arms, and legs (tetraplegia,
also known as quadriplegia). In an L3 injury, messages are stopped at the lower
back. This results in at least some paralysis of the legs and hips
(paraplegia).

SCIs are also described as complete and incomplete,
and an incomplete injury is further classified into four subsections. The
American Spinal Injury Association (ASIA) classifies SCIs as follows:

Classification of spinal cord injuries

Classification

Description

A

Complete: No feeling or movement of the areas of your body that are
controlled by your lowest sacral nerves. This means you do not have feeling
around the anus or control of the muscle that closes the anus. People with
complete SCI do not have control of bowel and bladder function.

B

Incomplete: Feeling but no movement below the level of injury,
including sacral segments that control bowel and bladder function.

C

Incomplete: Feeling and movement below the level of injury. More
than half of key muscles can move, but not against gravity. Moving against
gravity means moving up, for example, raising your hand to your mouth when you
are sitting up.

D

Incomplete: Feeling and movement below the level of injury. More
than half of key muscles can move against gravity.

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